I. Field of the Invention
This invention relates generally to a light source mechanism of a barcode scanner and, more specifically, to a light source mechanism of a barcode scanner that has a standing cylindrical lens in front of the laser diode, and a point type light source is extended into a stripe type light beam. A mirror or a thin film coating prism is installed between the collimating lens and the standing cylindrical lens to make the light beam be reflected at least once and propagate horizontally, pass through the standing cylindrical lens, and finally form a horizontal stripe type light beam. This mechanism can save the cost of a circuit board, and at the same time can offer more internal enclosure space for another design.
II. Description of the Prior Art
Heretofore, it is known that the light source of the barcode scanner is a laser diode. The point type expanding light beam of the known laser diode passes through a collimating lens and is transferred into a point type parallel light beam and then reaches a target barcode by being reflected by a mirror. The mirror rotates with a definite angle or vibrates to have the light xe2x80x9cpointxe2x80x9d move from left to right (or from right to left) on the target barcode to scan the barcode. The scanned image is reflected back to a xe2x80x9cpoint typexe2x80x9d receiver (photodiode sensor, for example) to be detected and decoded by the following electric components. The disadvantages of this design: a need to vibrate or rotate a mirror to send out the point type light source; the mirror might not be easy to adjust during the manufacturing process, and the mirror can be tilted or even disordered by collision.
The barcode scanner has a main circuit board located horizontally with a secondary circuit board standing vertically. A laser diode is soldered on the secondary circuit board to have the light beam inject horizontally. The light beam reaches to the barcode and is reflected back to a xe2x80x9cpoint typexe2x80x9d receiver (photodiode sensor, for example). During the manufacturing process, the two circuit boards must be assembled vertically to have the light beam eject out horizontally. The manufacturing cost is higher, and bad connections might occur between two circuit boards. Since the two vertically connected boards are inside the enclosure, the internal mechanical design is limited and can not be improved. With such limitations, it is difficult to have a special design on styling.
It is therefore a primary object of the invention to provide a light source mechanism of a barcode scanner to have light beam from laser diode as light source; goes through a collimating lens and a standing cylindrical lens (or multiple combination of different standing cylindrical lenses), the point type laser light source can become a stripe type light on the target barcode, the reflected light from barcode is focused by a condensing lens to a xe2x80x9clinearxe2x80x9d light receiver (CCD or CMOS sensor, for example), which can transfer the light signal into electrical signal, a circuitry on the backend can decode the electrical signal. The scheme has stronger light, farther projectile distance; projectile light is more focused and clear, thus easier for manufacturing and collision-resistant.
It is another object of this invention to provide a light source mechanism of a barcode scanner, a mirror or a prism is installed in front of the laser diode and the collimating lens that can change the direction of the laser beam to save the cost of another circuit board of the prior art. The prism of the present invention contains many inclined planes to change the direction of light beam; such scheme simplifies the assembly and offers more internal space for more variety of design.